Biomass Production and Nitrogen Uptake in Corn‐Ryegrass Systems

Abstract

AbstractCropping systems, plant growth stages, and applied N fertilizer rates all directly affect N uptake. A 2‐yr study was conducted to evaluate the effects of cropping system [monocrop corn (Zea mays L.) and corn intercropped with annual ryegrass (Lolium multiflorum Lam.)] on dry matter (DM) production and distribution and on N uptake and allocation in the plants during the development of corn. Each of these corn systems was produced on a fine sandy loam (Typic Humaquept), using an application of 270 kg N ha−1 in each spring. Zero N (control) and conventional N rate (180 kg N ha−1) treatments were included for monocropped corn with conventional drainage. Plant tissues of all treatments were sampled at six‐leaf, tasseling, and mid‐grain filling stages, and after physiological maturity. In both years, DM production and N uptake of intercropped corn were lower than, or not different from, the monocropped corn (depending on growth stage). The total N uptake and DM production of the intercropping system (corn + ryegrass + weeds) were greater than those of the monocrop system. Application of 270 kg N ha−1 resulted in 20% less N recovery than 180 kg N ha−1 with monocropped corn production using free drainage. Both the corn‐ryegrass intercropping system and applied N rates altered the allocation of DM and N among different parts of the corn plants. The ryegrass and weeds were not able to take up enough of the extra N after the high N rate was applied for two consecutive years. The effect of precipitation on annual ryegrass growth was an important factor in N uptake by the intercropping system.